Bimetallic Nanoparticles for Catalytic Hydrogenations...introducing tin ligands into polynuclear...
Transcript of Bimetallic Nanoparticles for Catalytic Hydrogenations...introducing tin ligands into polynuclear...
Bimetallic Nanoparticles for Catalytic HydrogenationsRichard D. Adams
Department of ChemistryUniversity of South Carolina
Columbia, SC 29208
Aromatization (Dehydrogenation) - Important Reforming Reactions
Catalyst Particle Sizes: 1-5 nm in diameter
1140Octane ratings
Commerical Catalysts are Pt-Sn or Pt-Re on Al2O3
Bimetallic NanoCatalysts in Petroleum Reforming
C7H16 + 4 H2
+ 3 H2
+ 3 H2
Ru-Ru = 2.854(3) Åin Ru3(CO)12
Ru Ru
Ru
MeC N
N CMe
+3 Ph3SnH
Ru Ru
RuPh3Sn
SnPh3
MeC N
N CMe
SnPh3
Ru Ru
RuPh3Sn
SnPh3
SnPh3
H
H H
H
H H + 2CO
-2 NCMe- 2CO
Ru1-Ru2 = 2.9629(4)ÅRu1-Ru3 = 2.9572(4)Ru2-Ru3 = 2.9906(4)
125 oC
Ru Ru
Ru SnPh2Ph2Sn
SnPh2
- 3C6H6
Ruthenium-Tin Clusters for Catalytic HydrogenationsMultiple Additions of HSnPh3 to Ru3(CO)10(NCMe)2
Oxidative-Addition of Ph3SnH to Ru5(CO)12(η6-C6H6)(µ5-C)
CRu Ru
Ru Ru
Ru+ Ph3SnH
68 °C
Ru Ru
Ru Ru
Ru
Ph3Sn
H
C- CORu Ru
Ru Ru
Ru
SnPh3
SnPh3
HH
C+
Ru5(CO)11(η6-C6H6)(SnPh3)(µ5-C)(µ-H) Ru5(CO)10(η6-C6H6)(SnPh3)2(µ5-C)(µ-H)2
Up to 5 Tin Ligands can be added to Ru5(CO)12(C6H6)(µ5-C), four SnPh2 and one SnPh3
Ru5(CO)7(η6-C6H6)(µ-SnPh2)4(SnPh3)(µ5-C)(µ-H)
CRu Ru
Ru Ru
Ru+ 5 Ph3SnH
127 °CC
Ru Ru
Ru Ru
Ru
SnPh2Ph2Sn
SnPh2
Ph2Sn
SnPh3
- 5 CO- 4 C6H6
H
PtRu5(CO)15(µ-XPh2)(µ6-C)
Pt-Sn = 2.631 ÅRu1-Sn = 2.607 Å
Pt-Ge = 2.470 ÅRu1-Ge = 2.446 Å
PtRu5(CO)16(µ6-C)
SnPh2 and GePh2 Groups can be introduced into Platinum-Ruthenium Carbonyl Cluster Complexes
Ru Ru
Ru Ru
Pt
Ru
Ru Ru
Ru Ru
Pt
Ru
XPh
Ph
(i) Ph3SnH, rtC C
(ii) Ph3GeH, 68 °CX = Sn or Ge
J. M. Thomas et al. Accts. Chem. Res. 2003, 36, 20.
HO2C
CO2H
H2CO2H
CO2H
trans,trans-muconic acid adipic acid
Pt2Ru10 nanoclusterson mesoporous silica
Bimetallic Clusters can be good precursors to Heterogeneous NanoCluster Catalysts on Supports
x-ray emission spectrum of nanoparticle
Activated trimetallic PtRu(CO)14(C)(SnPh2) cluster on Mesoporous silica yields trimetallic PtRu5Sn nanoparticles
Energy (keV)
Cou
nts
2520151050
60
40
20
0
Pt
PtPt
Pt
Sn
SnSn
Sn
RuRu
Ru
RuRu
Ru
Ru
Cu
CuCu
1.0 ± 0.2Sn
1.0 ± 0.1Pt
5.0 ± 0.3Ru
Atom ratio
200 oC
H2 ,2h38 Å mesoporous silica
Activated trimetallic PtRu(CO)14(C)(SnPh2) cluster on Mesoporous silica yields trimetallic PtRu5Sn nanoparticles
Hydrogenation of Dimethylterephthalate. Comparison of Activites for some metallic nanoparticle catalysts
COMe
OC
MeO
OC
OMe
OC
MeO
OCH2OHHOH2C
dimethyl terephthalate (DMT)
dimethyl hexahydroterephthalate (DMHT)
1,4-cyclohexanedimethanol (CHDM)
* Pd0 170oC H2 400 atm
* CuCr 200oC H2 40 atm
* Eastman ProcessPtRu5Sn 100oC H2 20 atm
0
10
20
30
40
50
60
70
80
90
100
Ru5PtSn [a]Ru5PtGe [a]Ru5Pt [a]Ru6Sn [b]
Our Conditions: 24h at 100oC,20 atm H2 Support: mesoporous Davison 923 Silica with 38 Å pores
conversion DMHT CHDM SP X SP Y
25 oC 1h
Pt(COD)2+2 HSnPh3
25 oC 30 min
Ru3(CO)10(NCMe)2+2 HSnPh3
New bis-SnPh3 Compounds are Precursors to excellent new Heterogeneous Nanoscale Hydrogenation Catalysts
(COD)Pt(SnPh3)2
Ru(CO)4(SnPh3)2
+H2 +H2 +H2
CDT CDD CDE CDA
The Effect Tin on Selective Hydrogenation of Cyclododecatriene CDT
* “RhSn2” was derived from Rh3(CO)6(SnPh2)3(SnPh3)3
The monoene, Cyclododecene,is the most valuable product
Conversion(disappearance of CDT)
R. D. Adams et al. Angew. Chem., 2007, 46, 8182.
More on The Tin EffectReaction of H4Ru4(CO)12 with HSnPh3 has provided a new
Series RuSn cluster complexes Ru4(CO)12-x(µ4-SnPh)2(µ -SnPh2)xx=0,2,3,4 for use as Catalyst Precursors
RuRu
SnPh
RuRu
PhSn
Ph2Sn
Ph2SnCO
SnPh2
RuRu
SnPh
RuRu
PhSn
Ph2Sn
Ph2SnCO
CO
H4Ru4(CO)12
Ph3SnH
125o C+
RuRu
SnPh
RuRu
PhSn
Ph2Sn
Ph2SnSnPh2
SnPh2
+RuRu
SnPh
RuRu
PhSn
+
Ru4Sn2 Ru4Sn4 Ru4Sn5 Ru4Sn6
Ru4Sn2
Ru4Sn6
10 nm
Ru4(CO)12(µ4-SnPh)2(µ-SnPh2)4
The Tin EffectRu4Snx Nanoparticles obtained from Ru4(CO)12(µ4-SnPh)2(µ-
SnPh2)x clusters are excellent catalysts
10 nm
200 oC
H2 ,2h38 Å mesoporous silica
Ru4Sn6 nanoparticles
Ru4Sn6 Ru4Sn4 Ru4Sn2 Ru6Sn PtRu5Sn
Solvent free conditions 2% metal loading H2 ≅ 30 bar, T = 373 K, t = 8h
With Ru4Sn6 the only product Is cyclododecene after 10 h.
Ru3Sn3
All Ru4Snx Catalysts exhibit high selectivity for Cyclododecene.Selectivity increases with the increasing tin content
0 5 10 15 20 25
0
10
20
30
40
50
60
conversion 1,9-cyclododecadiene cyclododecene cyclododecanen/
mol
%
time (h)
0
10
20
30
40
50
60
70
80
90
100n/m
ol%
Ru Sn Ru SnRu SnRu Sn Ru Sn Ru SnPt
0
10
20
30
40
50
60
70
80
90
100n/m
ol%
Ru Sn Ru SnRu SnRu Sn Ru Sn Ru SnPt
conversion
1,9-cyclododecadiene
cyclododecene
cyclododecane
conversion
1,9-cyclododecadiene
cyclododecene
cyclododecane
Nanoparticle on top is slightly larger than 2nm
Nanoparticles move in the during imaging.The two below the group of four fuse at the end.
High Resolution Scanning Transmission Electron Microscopy Images of Ru3Sn3 Nanoparticles on 38 Å silica mesopore
High Resolution Scanning Tunneling Microscopy STM Images of Ru3Sn3 on ultrathin SiO2/Mo(112) at +1.5 volts
SiO2/Mo(112)
200 oC
RuRu
RuPh2Sn SnPh2
Ph2Sn
J. Phys. Chem. 2008, 112, 14233
15 nm × 15 nm
SiO4 tetrahedra on Mo(112)
White triangles are Ru3Sn3 clusters
Individual Ru3Sn3 Clusters are revealed at higher resolutions
a
b6 nm × 6 nm
6 nm × 4 nm
[1 11]
[110]
c
d
3 D image
Ru-Sn≅ 2.7Å
Ru3Sn3 Clusters in close proximity
4.5 nm x 4.5 nm at 1.5 v
[-1-11]
[-1-10]
Yang - TAMU Grönbeck - Chalmers
1) Ph3SnH and Ph2SnH2 are good reagents forintroducing tin ligands into polynuclear metalcluster complexes
2) Clusters containing tin ligands can be precursors tobi- and trimetallic heterogeneous hydrogenationnanocatalysts
3) Tin containing nanocatalysts exhibit better reactionselectivity than the pure metals for some catalytichydrogenation reactions.
Conclusions
• Drs. Burjor Captain, Doug Blom, Ms. Eszter Trufan
• Prof. D. Wayne Goodman and Dr. Fan Yang at TAMU, STM measurements
• Prof. Sir John Meurig Thomas, Dr. Paul Midgley, Dr. Ana Hungria, Cambridge University (TEM)
• Dr. Robert Raja University of Southampton (catalysis)
$$$National Science Foundation
Acknowledgements